Wireline wipers

ABSTRACT

A WIPER ASSEMBLY IS DISCLOSED HEREIN THAT IS USEFUL IN CONNECTION WITH A WIRELINE THAT EXTENDS INTO A CONDUIT LOCATED IN A WELL BORE OR THE LIKE. THE WIPER ASSEMBLY INCLUDES A BODY THAT IS ADAPTED FOR CONNECTION WITH THE CONDUIT IN ENCIRCLING RELATIONSHIP TO THE WIRELINE. A DEFORMABLE WIPING ELEMENT IS POSITIONED IN THE BODY AND ARRANGED TO BE DEFORMED INTO SEALING ENGAGEMENT WITH THE BODY AND WITH THE WIRELINE. TO DEFORM THE WIPING ELEMENT, A PISTON IS SLIDINGLY POSITIONED IN THE BODY AND HAS AN UPPER END THAT ENGAGES, IN NON-SEALING RELATIONSHIP, THE WIPING ELEMENT. THE PISTON IS ARRANGED TO BE MOVED IN THE BODY IN RESPONSE TO A FLUID PRESSURE EXERTED THEREON. THE PISTON IS ALSO ARRANGED SO THAT THE WELL PRESSURE, TO WHICH THE PISTON IS EXPOSED, EITHER HAS NO EFFECT ON THE PISTON OR IS ARRANGED WHEREBY THE WELL PRESSURE TENDS TO MOVE THE PISTON INTO TIGHTER ENGAGEMENT WITH THE WIPING ELEMENT.

Sept. 20, 1971 w, READ EI'AL 3,606,341

, WIRELINE WIPERS Filed F6!)- 28, 1969 2 Sheets-Sheet l mvmvrons A/aeMA/v M4 P540 BY Moe's/41v La 690W ZJHLM ATTOPA/EY Sept. 20, 1971 N, w, READ ErAL 3,606,347

' v v WIRELINE WIPERS Filed Feb. 28, 1969 2 Sheets-Sheet 2 Z P Ira-4 1 INVENTORS Noe/144M MA @540 BY Maps/w A, CQOW I 4 (iLflkLM United States Patent O1 zfice 3,606,347 Patented Sept. 20, 1971 ABSTRACT OF THE DISCLOSURE A Wiper assembly is disclosed herein that is useful in connection with a wireline that extends into a conduit located in a well bore or the like. The wiper assembly includes a body that is adapted for connection with the conduit in encircling relationship to the wireline. A deformable wiping element is positioned in the body and is arranged to be deformed into sealing engagement with the body and with the wireline. To deform the wiping element, a piston is slidingly positioned in the body and has an upper end that engages, in non-sealing relationship, the wiping element. The piston is arranged to be moved in the body in response to a fluid pressure exerted thereon. The piston is also arranged so that the well pressure, to which the piston is exposed, either has no eifect on the piston or'is arranged whereby the well pressure tends to move'the piston into tighter engagement with the wiping element.

BACKGROUND OF THE INVENTION Various types of wireline wipers or strippers have been constructed in the past. Among these, US. Pat. No. 3,265,399 issued to Domer Scaramucci on Aug. 9, 1966, illustrates a stripper having concentrically arranged, two part wiper elements constructed from resilient material mounted in the stripper body. A piston, slidingly located in the body, is disposed in sealing engagement with the outer one of the wiping elements. The piston is arranged so that hydraulic =fiuid exerted in a chamber formed in the body moves the piston upwardly, shortening the outer one of the wiping elements and deforming it inwardly, forcing the inner element inwardly into sealing engagement with the wireline.

In the stripper shown in the Scaramucci patent, well pressure exerted on the lower end of the inner wiping element tends to deform the inner wiping element outwardly against the outer Wiping element. This force is then transmitted through the outer wiping element to the piston in a direction opposing the force exerted by the piston on the outer wiping element. This type of stripper has functioned in a generally satisfactory manner. If extreme well pressure is encountered, a leak may develop between the inner wiping element and the wireline. It has been found that such high pressure exerts a sufiicient force on the piston whereby the pump or other pressuring mechanism used to drive the piston upwardly cannot generate sufficient force to reestablish the seal between the inner wiping element and the wireline to stop the leak.

Another type of wiper or stripper presently in use is illustrated in US. Pat. No. 3,129,009 issued to Harry E. Simpson on Apr. 14, 1964. In this wireline wiper, the body is constructed in two parts and is provided with appropriate seals so that the outer part of the body is driven downwardly by an externally supplied fluid pressure, compressing the deformable wiping element into sealing engagement with the outer body portion and with the wireline. Well pressure exerted on the lower end of the wiping element, exerts an upwardly directed force thereon opposing the downward force developed by the Claims externally supplied fluid pressure. If an extremely high well pressure is encountered, and a leak develops between the wireline and the deformable wiping element, sufficient force cannot be developed by the external fluid pressure pump to reestablish the seal.

Thus, it is one object of this invention to provide an improved wiper assembly wherein the deformable wiping element can be deformed into sealing engagement With the wireline even in the presence of extremely high well pressure.

A further object of the invention is to develop an improved wireline wiper wherein well pressure is utilized to aid in deforming the seal-forming, wiping element.

Another object of the invention is. to providean improved wireline wiper assembly having an indicator that permits the ascertainment of the condition ofthe deformable wiping element.

SUMMARY OF INVENTION This invention provides an improved Wiper assembly for use in connection with a wireline extending into a conduit that is disposed in an oil and gas well or the like. The wiper assembly comprises: a hollow body'adapted to encircle the wireline and to be connected with the conduit; an annular piston moveably disposed in the body, the piston having upper and lower surfaces exposed to the pressure in the conduit; and, a wiping element constructed from an elastomer located in the body in encircling relationship to the wireline. The wiping element has a side wall engaging the body, an upper end supported by the upper end of the body and a lower end engaging the upper surface of the piston in non-sealing relationship; the Wiping element being deformable into engagement with the wireline upon movement of the piston toward the upper end of the body.

The foregoing and additional objects and advantages of the invention will become more apparent as the following detailed description is read in conjunction. with the accompanying drawings wherein like reference characters denote like parts in all views.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view, partly in elevation and partly in crosssection of wireline wiper assembly constructed in accordance with the invention.

FIG. 2 is a cross-sectional view taken generally along the line 2--2 of FIG. 1.

FIG. 3 is a cross-sectional view taken generally along the line 33' of FIG. 1.

FIG. 4 is a view, partly in cross-section and partly in elevation, illustrating another embodiment of wireline wiper that is also constructed in accordance with the invention.

FIG. 5 is a view, partly in cross-section and partly in elevation, illustrating still another-embodiment of Wiper assembly also constructed in accordance with the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings and to FIG. 1 in particular, shown therein and generally designated by the reference character 10 is a wireline wiper assembly. The assembly 10 includes a body 12, a deformable wiping element 14 disposed in the body 12 and a piston 31 6 slideably disposed in the body 12.

The body 12 comprises an upper body portion 18, a medial body portion 20 threadedly connected to the upper body portion 18 and a lower body portion 22 threadedly connected with the medial body portion 20. The lower body portion 22 is provided with threads 24 for threaded- 1y connecting the assembly with a conduit (not shown) that is disposed in a well bore (not shown). An O-ring seal 26 encircles the exterior of the upper end of the lower body portion 22. The seal 26 is in sliding and sealing engagement with the lower end portion of the piston 16.

An O-ring seal 28 encircles the interior of the medial body portion and is disposed in sliding and sealing engagement with the exterior of the lower end portion of the piston 16. The lower body portion 22, the medial body portion 20, the seals 26 and 28 and the lower end portion of piston 16 cooperate to form a chamber 30 in the assembly 10.

A pressure fitting 32 is threadedly connected to the medial body portion 20 in fluid communication with the chamber 30. The fitting 32 is provided so that a source of pressurized fluid such as a pump or gas cylinder (not shown), can be connected thereto for applying pressure in chamber 30'.

An indicator ring 34 encircles the exterior of the piston 16 within the medial body portion 20. The indicator ring 34 is visible through an opening 36 that extends through the wall of medial body portion 20. The indicator ring 34 moves with the piston 16 and therefore indicates the position of the piston 16 relative to the body 12.

A helical compression spring 38 is disposed in the medial body portion 20. The lower end of the spring 38 is in engagement with the indicator ring 34 and the upper end of the spring 38 is in engagement with the upper body portion 18. The spring 38 is designed to exert a downwardly directed force on the piston 16, biasing the piston 16 into the position shown in FIG. 1.

An O-ring seal encircles the lower interior end of the upper body portion 18 in sliding and sealing engagement with the upper end portion of the piston 16. In the embodiment illustrated in 'FIG. 1, the seals 26 and 40 preferably have equal sealing diameters on the piston 16 so that they define an upwardly facing surface 42 that is equal in area to the total of the downwardly facing surfaces 44 and 46 on the piston 16. Since the area of the surface 42 is equal to the total area of the surfaces 44 and 46, well pressure within the interior of the body 12 exerts equal upwardly and downwardly directed forces on the piston 16. In other words, the piston 16 is balanced or substantially balanced, if the surfaces are not exactly equal, with respect to well pressure within the body 12.

Identical upper and lower bushings 48 are located in the body 12 in engagement with the upper and lower ends of the wiper element 14. As can be clearly seen in FIG. 1, the bushings 48 are inverted with respect to each other when assembled in the wiper assembly 10. The lower bushing 48 is in engagement with the upwardly facing surface 42 of the piston 16. Since the bushings 48 are split as can be seen in FIG. 3, the lower bushing 48 does not sealingly engage either the wiper element 14 or the piston 16. Since the lower bushing 48 does not sealingly engage the piston 16, or the wiping element 14, well pressure within the assembly 10 is exerted on the upwardly facing surface 42 of the piston 16 and the lower end of the wiping element 14. The bushings 48 and wiping element 14 (see FIG. 2) are split to enable the bushings and the Wiping element 14 to be more readily replaced should they wear out during operation of the wireline wiper assembly 10.

To retain the wiping element 14 and the. upper bushing 48 in the body 12, a collar 50 is located in the upper portion 18 of the body 12. The collar 50* supports the bushing 48 and is retained in the upper body portion 18 by a yoke 52 that extends through the collar 50 and upper body portion 18 as illustrated in FIG. 3. To prevent the yoke 52 from becoming inadvertently dislodged from the wiper assembly 10, a pin 54, which is similar to a large safety pin, extends across the open end of the yoke 52.

4 OPERATION OF THE PREFERRED EMBODIMENT When wireline operations are to be performed in a well bore, the body 12 is connected by means of the threads 24 to the upper end of the conduit (not shown) that extends into the well bore (not shown). The wireline 56 which has a desired well tool (not shown) attached to the lower end thereof, is passed through the wireline wiper assembly 10.

After the wireline 56 has been lowered through [the wiper assembly 10', the lower bushing 48, wiping element 14, upper bushing 48 and the collar 50 are placed in the body 12 in encircling relationship to the wireline 56. The yoke 52 is then inserted through the body 12 to retain the collar 50 therein. The safety pin 54 is placed in the position shown in FIG. 3 to prevent the yoke 52 from coming out of the body 12.

If there is no pressure in the well, the wireline 56 can be lowered through the assembly 10 with little or no engagement between the wiping element 14 and the wireline 56. If there is pressure in the well, a pump (not shown) or a source of gas under pressure (not shown) is connected to the fitting 32 so that fluid under pressure is delivered into the chamber 30.

Pressure in the chamber 30 drives the piston 16 relatively upwardly, compressing the spring 38 and moving the lower bushing 48 into engagement with the lower end of the wiping element 14. As the piston 16 moves upwardly, the wiping element 14 is deformed radially into sealing engagement with the upper body portion 18 and with the wireline 56.

As previously mentioned, the piston 16 is balanced relative to the well pressure and as a consequence, the magnitude of the force developed on the piston 16 by the fluid in the chamber 30 need only be of sufficient magnitude to deform the wiping element 14 and spring 38. As the piston 16 travels upwardly, the indicator ring 34 travels upwardly therewith. Since the indicator ring 34 is visi'blethrough the opening 36 in the body 12 the piston position can be readily determined.

As the wiping element 14 wears due to the erosive effect of the wireline 56 passing therethrough, the fluid pressure in the chamber 30 maintains the force on the wiping element 14, continually deforming the wiping element 14 toward sealing engagement with the wireline 56. As the wiping element 14 wears away, the piston 16 moves upwardly and its position can be determined by observing the indicator ring 34, thus providing a continuous indication of the condition of the Wiping element 14.

As previously described, the lower bushing 48 is split and does not sealingly engage either the lower end of the wiping element 14 or the upwardly facing surface 42 of the piston 16. Therefore, the lower end of the Wiping element 14 is subjected to the pressure in the well. If sealing engagement between the body 12 and the wiping element 14 and between the wireline 56 and the wiping element 14 is initiated by the piston 16, well pressure acting across the lower end of the wiping element 14 will tend to increase the sealing engagement of the wiper 14 with the wireline 56 and with the body 12.

If the erosion of the wiping element 14, due to the movement of the wireline 56 therethrough, causes a leak between the wiping element 14 and the wireline 56, additional pressure can be applied in the chamber 30 to move the piston 16 upwardly and further deform the wiping element 14 to restore the seal between the wiping element 14 and the wireline 56. As previously mentioned, the piston 16 is balanced with respect to the pressure in the well and therefore, the only force that need be applied to the piston 16 is a force of a sufficient magnitude to deform the element '14 to reestablish the seal.

It can be appreciated by the foregoing, that the wiper assembly 10 can be effectively utilized to provide the desired seal between the wiping element 14 and the wireline 56, even in the presence of extremely high well pres sures. It will also be apparent that if a leak occurs, the seal can be readily established even in the presence of high well pressures.

DESCRIPTION OF THE EMBODIMENT OF FIG. 4

BIG. 4 of the drawing illustrates a structure of a wireline wiper assembly generally designated by the reference character 100. The wiper assembly 100 includes a body 102, a deformable wiping element 104 that is disposed in the body 102 and a piston 106 that is slideably positioned in the body 102.

The body 102 includes an upper body portion 108, a medial body portion 110 that is threadedly connected with the upper body portion 108 and a lower body portion 112 that is threadedly connected with the medial body portion 110. The lowermost end of the lower body portion 112 is provided with threads 114 for connecting the body 102 to a conduit (not shown) that is disposed in a well bore (not shown).

The piston 106 includes a lower external flange 116 that carries an O-ring seal 118 in sliding and sealing engagement With the interior of the lower body portion 112. At its upper end, the piston 1106 includes an outer flange 120 that carries an O-ring seal 122 in sliding and sealing engagement with the interior of the upper body portion 108. The sealing diameters of the O-rings 118 and 122 and the upwardly facing surface 124 on the piston 106 and the downwardly facing surface 126 thereon are of equal or at least substantially equal area affected by hydraulic pressure. Since the effective areas of the surfaces 124 and 126 are equal, the piston 106 is balanced with respect to well pressure within the body 102.

Encircling the piston 106 and positioned above the flange 116 is an indicator member 128. The indicator member 128 is visible through an opening 130 provided in the medial body portion 110. The indicator member 128 is arranged to travel with the piston 106 and therefore indicates the position of the piston 106 relative to the body 102.

A helical compression spring 132 encircles the exterior of the piston 106 and has its lower end in engagement with the indicator member 128 and keeps it in engagement with the flange 1 16 on the lower end of the piston 106. The upper end of the spring 132 is in engagement with an interior flange 134 formed in the medial body portion 110. As arranged, the spring 132 exerts a biasing force on the piston 106', urging the piston 106 toward the position illustrated in FIG. 4.

An O-ring seal 136 that is carried by the flange 134 is in sliding and sealing engagement with the exterior of the piston 106. The O-ring seals 122 and 136, in cooperation with the medial body portion 110 and the piston 106, form a chamber 138 within the assembly 100. A pressure fitting 140 is threadedly connected with the medial body portion 110 providing fluid communication with the chamber 138. The pressure fitting 140 is arranged for connection with a source of fluid under pressure that is external of the assembly 100.

Located in the body 102 between the wiping element 104 and the upper surface 124 of the piston 106 is a lower bushing "142. The lower bushing 142 is constructed in two parts so that it does not sealingly engage either the wiping element 104 or the piston 106. Further, the two part construction facilitates replacement of the expendable components of the assembly 100 during use. Since the bushing 142 does not for-m a seal with the element 104 of the piston 106, well pressure in the body 102 acts across the lower end of the element 104 and across the surface 124 of the piston 106.

The wiping element 104 is preferably constructed from an elastomer that provides high wear resistance, longest life, during the use of the assembly 100. The element 104 includes a side wall 144 that is disposed in juxtaposition with the interior of the upper body portion 108 and has a bore 146 extending therethrough that is sized to receive a wireline 148. The element 104 is split (see element 14 in FIG. 2) to facilitate its insertion on the wireline 148.

The upper end of the element 104 is in engagement with an upper bushing 150 that is constructed identically to the lower bushing 142. However, the upper bushing 150 is inverted when assembled in the assembly as shown in FIG. 4.

To retain the element 104 and the bushing 150 in the body 102, a collar 152 supportingly engages the upper bushing 150. A yoke 154 extends through the collar 152 and the upper body portion 108 to retain the collar 152 therein. A safety pin 156 prevents the inadvertent disengagement of the yoke 154 from the assembly 100.

OPERATION OF THE EMBODIMENT OF FIG. 4

The wireline wiper assembly 100 is assembled and operates in a manner very similar to that previously described in connection with the wireline assembly 10. In fact, the assembly 10 and the assembly 100 each contains a piston having equal upwardly facing and downwardly facing surfaces whereby the piston is balanced with respect to well pressure.

When it is desired to deform the wiping element 104 into sealing engagement with the wireline 148, pressure from an external source is applied through the fitting into the chamber 138. The pressure thus applied acts on the piston 106 to drive the piston 106 upwardly carrying the lower bushing 142 therewith and applying a force to the lower end of the wiping element 104. As a result of the upward movement of the piston 106 and bushing 142, the Wiping element 104 is deformed into sealing engagement with the body 102 and with the wireline 148.

As previously mentioned, the piston 106 is balanced with respect to well pressure in the body 102 and therefore, the magnitude of the well pressure is immaterial as far as the force that must be applied to the piston 106 to cause deformation of the Wiping element 104. It is possible, therefore, to restore the sealing condition of the wiping element 104, in the event that a leak does occur, regardless of the magnitude of the well pressure.

DESCRIPTION OF THE EMBODIMENT OF FIG. 5

FIG. 5 illustrates another embodiment of wireline wiper assembly generally designated by the reference character 200. The wiper assembly 200 includes a body 202, a deformable wiping element 204 disposed in the body 202 and a piston 206 slidably disposed in the body 202.

The body 202, includes an upper body portion 208, a medial body portion 210 threadedly connected with the upper body portion 208 and a lower body portion 212 threadedly connected with the medial body portion 210. The lower end of the lower body portion 212 is provided with a thread 214 for connecting the body 202 with a conduit (not shown) that is disposed in a well bore (not shown).

The lower body portion 212 carries an O-ring seal 216 that slidingly and sealingly engages the piston 206. A passageway 218 extends through the upper end of the lower body portion 212 and has its lower end in fluid communication with a pressure fitting 220 that is threadedly connected thereto. A pressure fitting 220 provides fluid communication between a chamber 222, the passage way 218 and an external source of fluid under pressure that is to be connected to the pressure fitting 220.

The chamber 222 is formed in the assembly 200 be tween the upper end of the lower body portion 212 and an outwardly extending flange 224 located on the piston 206. The flange 224 carries an O-ring seal 226 that slidingly and sealingly engages the interior wall of the medial body portion 212. Thus, the medial body portion 210, the O-ring seals 216 and 226, the lower body portion 212 and the piston 206 cooperate to form the chamber 222.

The upper end of the piston 206 is in sliding and sealing engagement with an 'O-ring seal 228 that is located in the interior wall of the upper body portion 208. The O-ring seals 216 and 228 have different sealing diameters on the piston 206. The O-ring seal 216 is larger in diameter than the O-ring seal 228 providing a lower surface 230 on the piston 206 that has an area greater than the area of an upper surface 232 located thereon. Since the surface 230, is larger in area than the surface 232, well pressure in the body 202 biases the piston 206 upwardly.

An indicator member 234 is disposed in the body 202 and has its lower end in engagement with the flange 224 on the piston 206. The indicator member 234 is visible through an opening 236 provided in the medial body portion 210.

Encircling the upper end of the piston 206 is a helical compression spring 238. The lower end of the spring 238 is in engagement with the lower end of the indicator member 234 and the upper end of the spring 238 is in engagement with the upper body portion 208. As arranged, the spring 238 biases the indicator member 234 and piston 206 relatively downwardly toward the position illustrated in FIG. 5.

The upper surface 232 of the piston 206 is in engagement with a lower bushing 240. The lower bushing 240 is constructed in two parts and is in engagement with the lower end of the wiping element 204. The two part construction of the lower bushing 240 provides a non-sealing relationship between the bushing 240, the wiping ele' ment 204 and the upper surface 232 of the piston 206. As a result, the upper surface 232 of the piston 206 is exposed to well pressure in the body 202.

The wiping element 204 is constructed similarly to the previously described wiping elements. Like the wiping elements 14 and 104, the wiping element 204 is constructed from an elastomer that is compatible with the fluids in the well. The wiping element 204 is split to facilitate its insertion on the wireline during the initial assembly and to aid in removal and replacement should replacement of the wiping element 204 be necessary during operation of the assembly 200. The wiping element 204 is deformable into sealing engagement with the interior of the upper body portion 208 and with a wireline 242 that extends through the assembly 200.

An upper bushing 244 supports the upper end of the wiping element 204. The upper bushing 244 is constructed identically to the lower bushing 240, but is inverted with respect to the bushing 240 when placed in the assembly 200.

To retain the wiping element 204 and upper bushing 244 in the body 202, a collar 246- is positioned in the upper body portion 208. The collar 246 is retained by a yoke 248 that extends through the upper body portion 208 and through the collar 246. A safety pin 250 is placed in the open end of the yoke 248 to prevent the yoke 248 from becoming inadvertently disengaged from the assembly 200.

OPERATION OF THE EMBODIMENT OF FIG. 5

The operation of the wireline wiper assembly 200 is essentially the same as the operation of the assemblies and 100. However, it should be pointed out that the piston 206 of the assembly 200 has a greater area on the lower surface 230 thereof than the upper surface 232 which results in well pressure biasing the piston 206 upwardly and thereby exerting a deforming force on the wiping element 204. Thus, the wiper assembly 200 may be referred to as self-energizing in that increases in well pressure are reflected as increases in force on the wiping element 204. As a result of the upwardly directed force on the piston 206 due to the differential areas, the well pressures encountered not only do not oppose the move ment of the piston 206 but, in fact, reduce the fluid pressure that must be applied in the chamber 222 to drive the piston 206 upwardly to restore the sealing engagement between the wiping element 204 and the wireline 242.

The embodiments described in detail hereinbefore are presented by Way of example only and it will be understood that many modifications and changes can be made thereto without departing from the spirit and scope of the invention.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A wiper assembly for use in connection with a wireline extending into a conduit that is disposed in an oil and gas well or the like, said assembly comprising:

a hollow body adapted to encircle the wireline, said body having an upper end and having a lower end arranged for connection with the conduit;

annular piston means movably disposed in said body, said piston means having upper and lower surfaces exposable to pressure in the well, wherein the upper and lower surfaces on said piston means exposed to the well pressure are of substantially equal area whereby the well pressure has a negligible effect on said piston means; and

a wiping member constructed from an elastomer and located in said body, said wiping member having a side wall engaging said body, an upper end supported by the upper end of said body and a lower end engaging the upper surface of said piston means in nonsealing relationship, said wiping member being deformable into engagement with the wireline upon movement of said piston means toward the upper end of said body.

2. The wireline wiper assembly of claim 1 wherein the upper and lower surfaces on said piston means exposed to the well pressure are of equal area whereby the well pressure has no effect on said piston means.

3. The wireline wiper assembly of claim 1 wherein the lower surface on said piston means is of greater area than the area of said upper surface whereby said piston means is biased toward said wiping means by the well pressure.

4. The wireline wiper assembly of claim 1 and also including pressure means for exerting a force on said piston means to move said piston means in a direction to deform said wiping element into engagement with the wireline.

5. The wireline wiper assembly of claim 4 wherein said piston means includes a surface portion exposed to said pressure means; and wherein said assembly also includes means located between said body and said piston means isolating said surface portion from the well pres sure.

6. The wireline wiper assembly of claim 5 and also including a spring member having one end engaging said body and another end engaging said piston means, said spring member biasing said piston means in a direction away from said wiping element.

7. The wireline wiper assembly of claim 6 and also including an indicator member moveable with said piston means indicating the piston means position whereby the deformation of said wiping element can be determined.

8. The wireline wiper assembly of claim 7 wherein said body has at least one opening in the wall thereof and wherein said indicator member is disposed within said body and a portion thereof is visible through said openmg.

9. A wireline wiper assembly for use in connection with a wireline extending into a conduit that is disposed in an oil or gas well or the like, said assembly comprising:

a hollow body adapted to encircle the wireline, said body having an upper end and having a lower end arranged for connection with the conduit;

an elastic wiping element arranged to encircle the wireline, said element being disposed in said body and having an upper end supported by the upper end of said body, a wall portion engageable with the wall of said body and having a lower end;

a piston exposable to well pressure slidingly disposed in said body between said element and the lower end of said body, said piston having an upper surface in non-sealing engagement with the lower end of said element and having a lower surface of equal area;

first and second seals between said body and said piston, said seals having equal seal diameters whereby said piston is unaifected by well pressure;

a third seal between said body and piston cooperating with one of said first and second seals to form a chamber in said body, said chamber having a surface portion defined by said piston; and

pressure means in communication with said chamber for introducing fluid into said chamber to move said piston toward the upperend of said body to deform said element into engagement with said body and wireline.

10. A wireline wiper assembly for use in connection with a wireline extending into a conduit that is disposed in an oil or gas well or the like, said assembly comprising:

a hollow body adapted to encircle the wireline, said body having an upper end and having a lower end arranged for connection with the conduit;

an elastic wiping element arranged to encircle the wireline, said element being disposed in said body and having an upper end supported by the upper end of 10 said body, a wall portion engageable with the wall of said body and a lower end;

a piston exposable to well pressure slidingly disposed in said body between said element and the lower end of said body, said piston having an upper surface in non-sealing engagement with the lower end of said element and having a lower surface of greater area than said upper surface;

first and second seals between said body and said piston, said seals having different seal diameters whereby said piston is moved toward said element by well pressure;

a third seal between said body and piston cooperating with one of said first and second seals to form a chamber in said body, said chamber having a surface portion defined by said piston; and

pressure means in communication with said chamber for introducing fluid into said chamber to move said piston toward the upper end of said body to deform said element into engagement with said body and wireline.

References Cited UNITED STATES PATENTS 2,479,265 '8/ 1949 Roshong 27727 3,222,075 12/1965 Haeber 27773X 3,375,013 3/1968 Grantom 2772 3,468,549 9/1969 f Wilson 2773 3,132,867 5/1964 Scaramucci i 2774X SAMUEL B. ROTHBER-G, Primary Examiner 

